Glass manufacturing – Processes – Forming product or preform from molten glass
Patent
1989-12-21
1991-05-21
Lindsay, Robert L.
Glass manufacturing
Processes
Forming product or preform from molten glass
65 6, 65 14, 65 601, 65141, 264 5, 264 7, 264 8, 425 6, 425 8, C03B 3700
Patent
active
050172077
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a method and apparatus for forming flakes of glass or flakes of other like material.
The method and apparatus are applicable equally to any material which would melt when heated and is capable of being formed into flakes. Flakes of glass and similar materials are increasingly being used for the reinforcement of plastics or other composite materials.
One method which has been employed in the past to form flakes of glass has involved forming a thin walled cylinder of molten glass and then collapsing the cylinder to fracture the glass film to form glass flakes. The glass flakes produced by such a method are not flat or planar, and thus are undesirable for those many purposes which comtemplate use of flat or planar flakes.
A method and apparatus for forming flakes of glass was disclosed in UK Patent Specification No. 989,671. This method is one in which the stream of heat softened material is fed vertically downwardly to a rotating distributor which throws out the heat softened material onto the walls of a downwardly facing annular cup. The cup forms part of a rotor which rotates at high speed and therefore gravity and centrifugal force cause the material to flow downwardly along the inner walls of the cup and then out from the bottom rim of the cup. This projects the material outwardly in the form of a film and this film is then broken up into flakes. It is suggested that the film can be broken up into flakes by mechanical means and the specification also described a method of breaking the film into flakes by blowing gas at high pressure in a direction so that it cuts through the film to break it up into flakes. This method and apparatus system has now been used for a number of years but it involves complex arrangements of heating and cooling means about the rotor and its surroundings. Moreover the glass flakes produced are often inconsistent in size and thickness.
SUMMARY OF THE INVENTION
According to the invention there is provided apparatus for forming flakes of material from a heated stream of molten material comprising means for feeding the stream in a downwardly direction into a rotating cup, the cup being arranged such that its opened mouth faces upwardly such that molten material within the cup is caused to flow over the upper edges of the cup and then flow outwardly in a radial direction due to centrifugal force, characterised in that the apparatus also includes a pair of spaced apart substantially parallel plates arranged about the cup such that the material leaving the cup by centrifugal force passes through a gap defined between the plates, the plates being mounted within a cyclone vacuum chamber arranged such that a vacuum is applied to the space between the plates to draw air from outside the chamber between the plates in a radial direction to prevent the molten material from touching the sides of the plate and to cool material until it reaches a solid state, and thereby pulling the material in a radial direction, keeping the material in a flat film and breaking it into small platelets.
Thus the molten material fed between the plate is prevented from rolling or rucking over.
Preferably the plates are in the form of two annular plates with cup mounted such that its rim lies between the plates.
Preferably the vacuum chamber is connected via its outlet to a cyclone precipitator separator and vacuum pump.
By suitable choice of speed of rotation of the cup, the distance between the two plates and choice of air flow through the vacuum chamber, the size and thickness of the flakes of material to be produced can be controlled.
Preferably the cup has tapered sides so that its top edge flares outwardly so that the passage of the molten material up the sides of the cup is aided by centrifugal force.
The apparatus can be used to produce flakes of many different materials which can be molten. Typically this material will be glass but the apparatus may equally be used with materials such as basalt, ceramics such as alumina, graphite, and metals such as lead.
REFERENCES:
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patent: 3257183 (1966-06-01), Slayter et al.
patent: 3325263 (1967-06-01), Day et al.
patent: 3346356 (1967-10-01), Anderson et al.
patent: 3607165 (1971-09-01), Guthrie
patent: 3644108 (1972-02-01), Russell
patent: 3883334 (1975-05-01), Cassidy et al.
Elvidge John H.
Watkinson Charles J.
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